From nobody Wed Feb 11 07:48:31 2026 Received: from out-189.mta1.migadu.com (out-189.mta1.migadu.com [95.215.58.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E87DF38BF64 for ; Thu, 22 Jan 2026 15:31:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.189 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769095921; cv=none; b=fdvtLxgB9TOUx5gmbuobSeZ/hxwDgoVcUZyWl2cBLihHZw14tRdGExwIk+mpLQrKEwsI6NO/jHSQYAw0HSpVe0jWjH2kZKhCqCJO+xG0rZh0S7urdSRr79GbBf9KPed+RyALCJlNQRjzXSKpQa9YCVM8yLC1XzACX7bmkL9t9WE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769095921; c=relaxed/simple; bh=pRa//8PzCcBD7X16JjPzDoiWbVbFV9R8qJmQeWgEkcU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s4mlAxgoJVyQjfhOrwReFy4VlhiN1PCfckzlq/TTx34mGySK49tBJ9tpctFbLMKpZv8TWkLYx/qJkYUZo9VdM6otW76IbFtgEtGgLqIxAnwEWAFblUwjtacv8uh27rBmTA8G9bmSDdQ4w5McvdzryCo+yZ0qT3wK5hsvqXJkwJU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=D8BT5f9G; arc=none smtp.client-ip=95.215.58.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="D8BT5f9G" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769095915; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zfS4wRyf/VRnjwnPX4tgHWNsIgrX88DqFs7Pj+omr4c=; b=D8BT5f9Gm42ACxpty+gumNX4BsodB+xW9AZamL4kiTmTus1d391WQtBJRgk84lQ/68Zl2I DkBI0uJG/In3afQy2hEVaU41Ush0RNT4Hecq4lOI19wkTFDUlwtgauMw7o10uxGhnwU3vf xRZ9CpjVZbBAC/2LLdV7kHE+0V82Q3M= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Leon Hwang , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 1/2] bpf: Disallow BPF_F_LOCK with mixed special fields and centralize flag checks Date: Thu, 22 Jan 2026 23:31:19 +0800 Message-ID: <20260122153120.69249-2-leon.hwang@linux.dev> In-Reply-To: <20260122153120.69249-1-leon.hwang@linux.dev> References: <20260122153120.69249-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Disallow combining BPF_F_LOCK with map values that contain special BTF fields other than bpf_spin_lock (e.g. kptr or uptr). Such mixing may lead to subtle or undefined behavior in map value updating. Reject these combinations early by returning -EOPNOTSUPP. Centralize map update flag validation in bpf_map_check_op_flags() and reuse it across array, hash, local-storage, and task-storage map update paths. Explicitly reject incompatible BPF_NOEXIST/BPF_EXIST combinations and invalid BPF_F_LOCK usage to keep flag validation consistent and eliminate duplicated per-map checks. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 7 +++++++ kernel/bpf/arraymap.c | 11 ++++------- kernel/bpf/bpf_local_storage.c | 7 ------- kernel/bpf/bpf_task_storage.c | 3 --- kernel/bpf/hashtab.c | 8 +++----- 5 files changed, 14 insertions(+), 22 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 5936f8e2996f..c5863487ee73 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3935,9 +3935,16 @@ static inline int bpf_map_check_op_flags(struct bpf_= map *map, u64 flags, u64 all if ((u32)flags & ~allowed_flags) return -EINVAL; =20 + /* BPF_NOEXIST and BPF_EXIST are mutually exclusive. */ + if ((flags & (BPF_NOEXIST | BPF_EXIST)) =3D=3D (BPF_NOEXIST | BPF_EXIST)) + return -EINVAL; + if ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_L= OCK)) return -EINVAL; =20 + if ((flags & BPF_F_LOCK) && btf_record_has_field(map->record, ~BPF_SPIN_L= OCK)) + return -EOPNOTSUPP; + if (!(flags & BPF_F_CPU) && flags >> 32) return -EINVAL; =20 diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 67e9e811de3a..1cff40f109cd 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -366,10 +366,7 @@ static long array_map_update_elem(struct bpf_map *map,= void *key, void *value, struct bpf_array *array =3D container_of(map, struct bpf_array, map); u32 index =3D *(u32 *)key; char *val; - - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST)) - /* unknown flags */ - return -EINVAL; + int err; =20 if (unlikely(index >=3D array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ @@ -379,9 +376,9 @@ static long array_map_update_elem(struct bpf_map *map, = void *key, void *value, /* all elements already exist */ return -EEXIST; =20 - if (unlikely((map_flags & BPF_F_LOCK) && - !btf_record_has_field(map->record, BPF_SPIN_LOCK))) - return -EINVAL; + err =3D bpf_map_check_op_flags(map, map_flags, BPF_EXIST | BPF_F_LOCK); + if (unlikely(err)) + return err; =20 if (array->map.map_type =3D=3D BPF_MAP_TYPE_PERCPU_ARRAY) { val =3D this_cpu_ptr(array->pptrs[index & array->index_mask]); diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index e2fe6c32822b..80b50091cbbf 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -493,13 +493,6 @@ bpf_local_storage_update(void *owner, struct bpf_local= _storage_map *smap, unsigned long flags; int err; =20 - /* BPF_EXIST and BPF_NOEXIST cannot be both set */ - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || - /* BPF_F_LOCK can only be used in a value with spin_lock */ - unlikely((map_flags & BPF_F_LOCK) && - !btf_record_has_field(smap->map.record, BPF_SPIN_LOCK))) - return ERR_PTR(-EINVAL); - if (gfp_flags =3D=3D GFP_KERNEL && (map_flags & ~BPF_F_LOCK) !=3D BPF_NOE= XIST) return ERR_PTR(-EINVAL); =20 diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c index a1dc1bf0848a..21d84818e64e 100644 --- a/kernel/bpf/bpf_task_storage.c +++ b/kernel/bpf/bpf_task_storage.c @@ -125,9 +125,6 @@ static long bpf_pid_task_storage_update_elem(struct bpf= _map *map, void *key, struct pid *pid; int fd, err; =20 - if ((map_flags & BPF_F_LOCK) && btf_record_has_field(map->record, BPF_UPT= R)) - return -EOPNOTSUPP; - fd =3D *(int *)key; pid =3D pidfd_get_pid(fd, &f_flags); if (IS_ERR(pid)) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 3b9d297a53be..2f6ed3e80308 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1093,9 +1093,9 @@ static long htab_map_update_elem(struct bpf_map *map,= void *key, void *value, u32 key_size, hash; int ret; =20 - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST)) - /* unknown flags */ - return -EINVAL; + ret =3D bpf_map_check_op_flags(map, map_flags, BPF_NOEXIST | BPF_EXIST | = BPF_F_LOCK); + if (unlikely(ret)) + return ret; =20 WARN_ON_ONCE(!bpf_rcu_lock_held()); =20 @@ -1107,8 +1107,6 @@ static long htab_map_update_elem(struct bpf_map *map,= void *key, void *value, head =3D &b->head; =20 if (unlikely(map_flags & BPF_F_LOCK)) { - if (unlikely(!btf_record_has_field(map->record, BPF_SPIN_LOCK))) - return -EINVAL; /* find an element without taking the bucket lock */ l_old =3D lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets); --=20 2.52.0